Implementation of online classes during national school closure due to COVID‐19 and mental health symptoms of adolescents: A cross‐sectional survey of 5000 students

Abstract Aim Online classes were implemented in numerous schools during the school closure due to COVID‐19. The present study examined the relationship between online classes during national school closure and mental health symptoms after the reopening of schools. Methods We conducted a cross‐sectional survey from October 1 to November 7, 2020 using an anonymous self‐reported questionnaire to evaluate 21 junior and senior high schools in the Saitama prefecture of Japan. Out of the 5538 students who were recruited, 5000 agreed to participate. The relationship between the implementation of online classes and mental health symptoms (emotional symptoms, psychotic experience [PE], and smartphone addiction) was evaluated using mixed‐effect logistic regression models, while controlling for individual and class‐level covariates (e.g., gender, grades). Results Implementation of online classes was reported by 78.2% of classroom teachers, and it was associated with lower rates of emotional symptoms (OR = 0.79, 95% CI = 0.63–0.99, p = 0.040) and smartphone addiction (OR = 0.79, 95% CI = 0.65–0.96, p = 0.020), but not related to PE (OR = 0.91, 95% CI = 0.61–1.36, p = 0.637). Conclusions Implementing online classes during the national school closure might have had a potential protective effect for adolescents' mental health symptoms (especially emotional symptoms and smartphone addiction) after the reopening of schools during the ongoing COVID‐19 pandemic.


INTRODUCTION
During the COVID-19 pandemic, schools closed worldwide to prevent the spread of the infection. Previous studies have indicated that mental health symptoms in adolescents worsened during school closures. [1][2][3][4][5][6][7] These mental health symptoms have not improved even since schools were reopened. After schools were reopened, the estimated suicide rate among Japanese youth increased 1.49-fold compared to the pre-pandemic period, based on the data of suicides in Japan between November 2016 and October 2020 published by Psychiatry Clin. Neurosci. Rep. 2022;1:e17.
wileyonlinelibrary.com/journal/pcn5 the Ministry of Health, Labour, and Welfare. 8 The well-being of children and adolescents may not have improved during the period between school closure and reopening. 9 The national school closure may have continued to affect students' overall activities (due to reduction of learning content and cancellation of school events), lifestyle, peer relationships, and mental health symptoms even after schools reopened. These findings suggest the need to investigate the factors that contributed to the prevention of mental health symptoms in adolescents during the school closure.
Implementing online classes during the school closure may have had a protective effect on mental health, partly through the maintenance of academic achievement and daily routines and the increase in opportunities for social interaction with peers and teachers. 1,4,[10][11][12][13][14] However, existing studies found mixed results regarding the relationship between online classes and mental health symptoms. Some studies conducted more than 9 months after the pandemic indicated worsened mental health during online classes, [15][16][17] whereas another study conducted within 6 months reported the opposite result. 18 These differences may be attributed to the survey period. In addition, research was limited to the local-level school closure, such as geographical region or school, and a crosssectional analysis. In the early phase of the COVID-19 pandemic, almost all of the schools in Japan were closed from late March to May 2020 and reopened in June 2020 in response to requests from the national and local governments. 19 No study has examined the relationship between online classes during the national school closure and mental health symptoms after schools were reopened.
The present study focused on emotional symptoms, psychotic experience (PE), and smartphone addiction as mental health symptoms.
Previous findings suggested that adverse events, such as natural disasters and social deprivation, are associated with increased mental health symptoms among adolescents. 10,[20][21][22] During the ongoing adverse event, COVID-19, it is important to investigate whether implementing online classes has a potential protective effect on these mental health symptoms. However, mixed results were reported regarding the relationship between online classes during the local school closure and emotional symptoms and depression or anxiety. [16][17][18] In addition, no study has examined the relationship between online classes and PE or smartphone addiction. We aimed to investigate the relationship between online classes during the national school closure and mental health symptoms after schools reopened. We hypothesized that online classes during the national school closure would be related to lower rates of later mental health symptoms.

METHODS
This study employed a cross-sectional survey design using an anonymous questionnaire to evaluate 21 private schools (N = 9 junior and N = 12 senior high schools) in Saitama prefecture, which is a large prefecture with a population of approximately 7.3 million. The study period was from October 1 to November 7, 2020, and it was approximately 5-6 months after the national school closure due to the first wave of the pandemic in Japan. Our research was conducted through cooperation with the Association for Saitama Private Junior and Senior High Schools and the heads and administrators of Saitama prefecture. Almost all private junior and senior high schools (≥98%) were closed in Japan. 19 The rate of school closure in Saitama prefecture was higher than in other prefectures, 19 probably because Saitama prefecture is located in a relatively high COVID-19 incidence area in Japan. For the purpose of the present study, we elected no as the reference for statistical analysis.
Emotional symptoms were measured using a subscale of the selfreported Strengths and Difficulties Questionnaire (SDQ). 23 The emotional symptoms include five items scored as follows: 0 for "not true," 1 for "somewhat true," and 2 for "certainly true." The total score ranges from 0 to 10 and is dichotomized based on the original "abnormal" cutoff thresholds (≥7). 23 The reliability and validity of the Japanese version of the self-reported SDQ have been confirmed. 24 The original "abnormal" cutoff threshold for the emotional symptoms corresponds to approximately the top 10% of the Japanese adolescent population before the pandemic (https://ddclinic.jp/SDQ/standardvalueinjapan. html), while the Japanese version of the self-reported SDQ has no standardized cutoff threshold. Therefore, to obtain a finding that helps to compare results across countries during the COVID-19 pandemic, we employed the original "abnormal" cutoff threshold. PE was assessed using one question that referred to the past year ("Please give the answers about yourself over the past year."): "Have you ever heard voices that other people cannot hear?" (Auditory hallucination). Possible responses were "no," "yes, probably," or "yes." We defined "yes" as the presence of PE. This self-reported question about auditory hallucination demonstrates good positive and negative predictive validity, not just for clinical interview-verifiable auditory hallucination but also for other PEs. 25 Smartphone addiction was measured using the Smartphone Addiction Scale-Short Version (SAS-SV). 26,27 SAS-SV comprises 10 items scored on a six-point Likert scale, ranging from "strongly disagree" (1) to "strongly agree" (6). The score was calculated by summing all responses, with a possible range of 10-60. The cutoff value of smartphone addiction is ≥31 and ≥33 for male and female participants, respectively. 26,27 Covariates included students' grades, gender ("male," "female" or "other"), class size, and remote consultation for students from classroom teacher during the national school closure. Grades and gender were added as basic demographic factors. Class size was added as an environmental factor concerning the degree of resource concentration in the educational setting for individual students during the COVID-19 pandemic. A previous study in Japan, before the COVID-19 pandemic, suggests that a larger class size was associated with lower academic performance, lesser support from teachers, and increased mental health symptoms. 28 As an indicator of the supports provided by teachers during the national school closure, other than online classes, remote consultation for students from the classroom teacher was included as a covariate. The classroom teachers (N = 133) were asked about remote consultation for students during this period ("Did you offer consultation to students online or by phone?"). Possible responses were "yes," "no," or "unknown." Statistical analyses were conducted using R Version 4.1.2.
Responses from students and teachers were linked as multilevel  Table 1 shows the descriptive statistics. Implementation of online classes was reported by 78.2% of classroom teachers. Prevalence of emotional symptoms, PE, and smartphone addiction was 18.9%, 5.8%, and 33.1%, respectively.

RESULTS
The results of the multiple logistic regression analyses are presented in Table 2 In addition, higher grades were associated with higher rates of emotional symptoms and smartphone addiction, but related to lower rates of PE (Table 2).

DISCUSSION
To the best of our knowledge, this is the first study to investigate the relationship between implementation of online classes during the national school closure and the mental health symptoms after schools reopened. This relationship was observed in emotional symptoms and smartphone addiction, but not in PE.
Online classes were found to be associated with lower rates of some mental health symptoms. Our findings were consistent with those in a study conducted within 6 months after the pandemic. 18 However, they were not consistent with studies conducted after more than 9 months. [15][16][17] Additionally, online classes may have had a protective effect on mental health symptoms for school closure at the national level, rather In addition, older adolescents were more likely to have emotional symptoms and smartphone addiction, but less likely to have PE, compared to younger adolescents. These results were in line with the findings on the pre-pandemic 34-37 and post-pandemic periods. 4,5,12,38 However, the increasing trend of mental health symptoms between the pre-and post-pandemic periods was more substantial, particularly in young age groups than in other age groups. 38 Thus, further provision of developmentally appropriate support for youth may be needed during the COVID-19 period.
This study has several implications for researchers, clinicians, and educators. Future research needs to examine whether the effect of online classes on mental health symptoms depends on the phase of pandemic or level of school closure. It is also necessary to investigate whether the lack of online classes is related to later mental health symptoms mediated by academic performance, daily routines, and social interaction. We believe that our study provided valuable findings for the school community through the cooperation with schoolteachers of the

CONFLICT OF INTEREST
The authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT
The availability of the data in this study is not open access due to the provisions of the ethics committee and the extent of the participants' consent. If readers wish to apply for the use of data, they must contact the corresponding author and consult the Ethics Committee, Faculty of Medicine, The University of Tokyo.